Denis Diderot was a philosopher and the chief editor of the Encyclopedia, or Reasoned Dictionary of the Sciences, Arts, and Trades, a key work of Enlightenment thought. He wrote extensively on religion and atheism, philosophical materialism, art, literature, and education. He is of particular interest to libertarians for his opposition to censorship, colonialism, slavery, sexual restrictions, and religious intolerance. Often he received no credit for his efforts because many of his works were not published until after his death, many were anonymous, and the authorship of still others remained long in dispute.

Diderot was born in Langres, Champagne, and received a Jesuit education. Although he prepared for a degree in theology, he abandoned Catholicism early in life and embraced an open, often strident atheism. His 1749 Letter on the Blind expanded on the empiricist philosophy of John Locke and argued that all ideas must originate with the senses and that, by implication, neither innate ideas, nor God, nor divine revelation was real.

Diderot’s work earned him a stay in the Vincennes prison, an experience that solidified his hatred of censorship and arbitrary power. Although his most influential writings are in epistemology, metaphysics, and aesthetics, his political thought is likewise of great interest. Diderot used commentaries on both the ancient and contemporary worlds to expound a variety of ideas that have since become central to libertarian thinking. For example, in his Essay on the Life of the Philosopher Seneca, Diderot wrote,

Tyranny imparts a brutish character on every sort of action; even language is not exempt from its influence. Indeed, is it really of no consequence for a child to hear around his cradle either the pusillanimous murmur of servitude, or the noble and proud accents of liberty?

The notion that control over language and education means control over the people has become important to the modern libertarian movement.

Yet just as often, Diderot’s ideas are far removed from the classical liberal thinking of his era and are more akin to those of Jean‐​Jacques Rousseau, the 18th century’s most significant exponent of what would later be termed positive liberty and whom some commentators regard as the period’s most significant defender of collectivism.

An example of Rousseau’s influence on Diderot can be found in his writings on Tahiti, which Europeans had only recently discovered and which Diderot imagined as a sexually liberated—albeit communist—utopia. His Supplement to the Voyage of Bougainville described a world free of coercion and even of most standards of modesty in dress and behavior. He implored Europeans not to interfere with the natural community of property and of women that were to be found on the island—which, critics have pointed out, Diderot never actually visited.

As head of the vast Encyclopedia project, Diderot struggled with the complex censorship of Old Regime France to produce a product that contained not only the distilled knowledge of his time, but also piquant commentaries on government, freedom of religion, and free expression. An enduring question in Diderot’s thought lies in the tension between the Encyclopedia, with its praise of industry and material progress, and the Supplement to the Voyage of Bougainville, which instead glorifies a lost ancestral liberty. Diderot was, however, always critical of entanglements between church and state, and he remains famous for his quip that “Man will never be free until the last king is strangled with the entrails of the last priest.”

Further Readings

Diderot, Denis. Oeuvres. Laurent Versini, ed. Paris: R. Laffont, 1994–1997.

Encyclopédie ou Dictionnaire raisonné des sciences, des arts et des métiers. Denis Diderot, Jean Le Rond d’Alembert, eds. CD-ROM version. Marsanne, France: Redon, 1999.

Furbank, P. N. Diderot: A Critical Biography. London: Secker & Warburg, 1992.

Jason Kuznicki
Originally published